Enhanced memory properties of HfO2-based ferroelectric capacitor by inserting Al2O3/ZrO2 stack interfacial layer

Abstract

HfO2-based ferroelectrics have been regarded as a promising material to integrate into a gate stack of silicon-based field-effect-transistors (FETs). However, a narrower memory window (MW) and poor endurance caused by an undesirable interfacial layer (IL) impede the further adoption. In this study, the ferroelectric metal–oxide–semiconductor capacitor with high-k Al2O3/ZrO2 stack IL was constructed to optimize the memory characteristics. The robust MW of 1.64 V under a low operating voltage of ±2.5 V was achieved. In addition, the excellent endurance was demonstrated with an available MW of 1.10 V after 108 cycles. Such improvement is attributed to the surface passivation and seed effect by the inserted Al2O3 and ZrO2, respectively. The Al2O3/ZrO2 stack IL stabilizes the ferroelectric orthorhombic phase to enhance the MW and suppresses the charge trapping to improve the reliability. This work proposes an effective method to optimize the memory characteristics for ferroelectric FETs.